Cell-based emergency call systems and methods

Abstract

A satellite-based cellular communication system (100) is used to provide emergency services to subscriber units located anywhere on the earth. The surface of the earth is divided into defined areas and emergency codes are assigned to each one of the defined areas. As subscriber units (150) move relative to the surface of the earth, the satellite-based cellular communication system (100) updates the emergency codes stored in the subscriber units (150) as required based on the subscriber unit's current location. The subscriber unit (150) uses the stored emergency codes to determine when a user is requesting emergency services and prioritizes the call accordingly.

What is claimed is: 
     
       1. A method for operating a gateway in a satellite communication system to provide emergency codes to a subscriber unit in the satellite communication system, comprising the steps of: (a) dividing earth's surface into defined areas identified by location area codes (LACs);   (b) assigning an emergency code to each of the defined areas, the emergency code identifying an emergency service center (ESC) when emergency services are provided for a particular LAC;   (c) receiving a registration message from the subscriber unit, the registration message comprising a LAC;   (d) determining from the registration message a home gateway for the subscriber unit;   (e) determining whether the subscriber unit has moved to a defined area with an emergency code that is different than the one currently assigned to the subscriber unit;   (f) transmitting a new emergency code to the subscriber unit, when the subscriber unit has a new LAC associated with it; and   (g) receiving an emergency service request message from the subscriber unit;   (h) determining a more accurate location of the subscriber unit;   (i) establishing a routing priority; and   (j) routing an emergency message to an ESC.